Merge remote-tracking branch 'remotes/juanquintela/tags/migration/20170601' into staging

migration/next for 20170601

# gpg: Signature made Thu 01 Jun 2017 17:51:04 BST
# gpg:                using RSA key 0xF487EF185872D723
# gpg: Good signature from "Juan Quintela <quintela@redhat.com>"
# gpg:                 aka "Juan Quintela <quintela@trasno.org>"
# Primary key fingerprint: 1899 FF8E DEBF 58CC EE03  4B82 F487 EF18 5872 D723

* remotes/juanquintela/tags/migration/20170601:
  migration: Move include/migration/block.h into migration/
  migration: Export ram.c functions in its own file
  migration: Create include for migration snapshots
  migration: Export rdma.c functions in its own file
  migration: Export tls.c functions in its own file
  migration: Export socket.c functions in its own file
  migration: Export fd.c functions in its own file
  migration: Export exec.c functions in its own file
  migration: Split qemu-file.h
  migration: Remove unneeded includes of migration/vmstate.h
  migration: shut src return path unconditionally
  migration: fix leak of src file on dst
  migration: Remove section_id parameter from vmstate_load
  migration: loadvm handlers are not used
  migration: Use savevm_handlers instead of loadvm copy

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>